Work is proposed on the analysis of the patterns of macromolecular biosynthesis in cells infected with reovirus, vaccinia virus, and Rous sarcoma virus. Among the projects to be investigated are: sequencing of reovirus messenger RNA molecules; studies on the nature of ts mutations that lead to inability to synthesize reovirus double-stranded RNA; studies on the anamalous electrophoretic migration behavior of hybrid double-stranded RNA molecules formed by mutant and wild type reovirus RNA; studies on the translation of reovirus messenger RNA in in vitro protein synthesizing systems; studies on the mechanism by which interferon inhibits the multiplication of reovirus; studies on the mode of induction of interferon by reovirus and reovirus ts mutants; studies on the in vitro synthesis of vaccinia virus messenger RNA by vaccinia cores and of the nature of the poly A sequences in this messenger RNA; studies on the in vivo transcription of Rous sarcoma virus RNA into DNA and on the intracellular transcription of Rous sarcoma virus RNA from integrated DNA; studies on the changes in the polypeptide and glycopolypeptide complements of the plasma membranes of chick embryo fibroblasts in the process of being transformed by Rous sarcoma virus; morphological studies on immature and mature Rous sarcoma virus particles; and studies on the nature of RNA tumor virus RNA with particular reference to a comparison of the sizes of the large subunits of transforming and nontransforming viruses.